Bump urllib3 from 1.25.3 to 1.26.18

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.3 to 1.26.18.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.25.3...1.26.18)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements3.txt

@@ -33,6 +33,6 @@ python-json-logger==0.1.11
 PyYAML==5.1
 six==1.12.0
 statsd==3.2.1
-urllib3==1.25.3
+urllib3==1.26.18
 Werkzeug==0.15.5
 omnibot-receiver==3.1.4